Automatic telephone system



INVENTOR Wmv-Rio T POWELL ATTORNEY lW. T. POWELL' AUTOMATIC TELEPHONE SYSTEM Aug. '1, w23.

Filed Aug. 25, 1920 2 Sheets-Shet 2 MTL.

.Ww OPUMT- LOU INVENTOR i `WmFRx-:D T POWELL ATTORNEY Patented Aug'. 1223.

WINGRED T. POVJELL, O11" ROCHESTER, NEUW YORK, ASSIGNOR TO TH STROMBERG CARLSON' TELEPHONE ItANUFAOTURING CQEIPANY, OE' ROCHESTER, NEW YORK,

A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE` Application filed August 25, 192

T 0 all eli/om t may concern.'

Be it known that l, llllirrnnn T. POWELL, a citizen ofthe United States, residing at Rochester, in the .county of Monroe and State of New York, have invented certain new and usetul improve-ments in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.l

This invention relates 'to telephone systems, and more vparticularly to :telephone systems employing automatic switches in completing telephone connection-s between ycalling and called` subscribers.

'In one. type of automatic telephone systems 'now Lin use, the automatic switches are adjusted in response to directive impulses caused by the Ainterruption ot an impulse circuit including the two sides-ot the call` ing subscrihers line in series. vIn such arrangementsitis necessary to distinguish between momentary 'interruptions ot thesubscribers line at thetime otthetransmission of directive impulses and the long inter-l ruption of thesubscribers line at the termination ot acall, which long interruption ot the line may be referred to as a release impulse.

`ln systems of the present time an arrange-` ment of fast and slow releasing relays are employed to distinguish between these various kindsk of impulses, and while the result is accomplished by the use of these slow relays they must be adjusted to operate on suchnarrow time limits that they will not operatesatisfactorily with substation impulse senders that operate slowly or very rapidly.

The present invention has for its purpose the elimination of the slow operating relays in connection with the setting and release ot numerical switches, 'and replaces them by tast acting relays which are con-- trolled .by fone or more mechanical timing devices. In such :a system it is also contemplated to eliminate the sequence controlling device which is commonly referred to f as a side switch. l y

In the drawingswith Fig. 1 placed at the lett of Fig. 2, there is diagramatically represented a portion of a. telephone system employing the present invention. At the lett of Fig. 1 there is represented a subscribers substation circuit and line, as well as a line switch individual to this line.

Serial No. 405,320.

Between the dottedlines of F ig. 1 there is 1presented a circuit arrangement for relayingV or repeating impulses to. a distant Vottico known as a repeater'. This line switch and repeater are herein represented as `located at the same o'iice. At the extreme right of F ig. 1 and the left of Fig. there is represented a selector switch located at aidistant otlice `herein referred to as oitice tti the rightot the dotted linein Fig. 2 there is represented a connector switcli,.also located at otlice :#2, and a called lineand its-sub-` station circuits. Y

It will loe understood that in a large svstem i'irst and a second numerical switch or 'selector of the character shown in Figs. 1 and 2 will be interposed between the line switch and repeater at otlice .#1, but the arrangement of these numerical switches forms no part of the present invention. i The line switch referred to in this system may be oi 'the structure disclosed in the patent to Clement, #1,10T,153, issued rAug. 11, 1911, and the operating` circuits 'of this switch may be of the design in which the brushes of the switch remain in engagement with the trunk terminals last used and may be similar to those shown in the patent `to Lamb, 7t"':1,193,1i50, 'patented Aug. 1, 1916. The structure of the selector switch may be substantially similar to that disclosed in the patent to ieith, et al. #815,321, issued Mar. 13, 1905, and the connector switch is similar to that disclosed in the patent to Keith, et al. #815,176, patented Mar. 13, 1906, when said last named switches have been modified to operate in i tem without side switches.

The relay of the repeater is or the 'type commonly referred to as electropolarized. The lernt hand winding oi' this relay is inetiicient and will ynot attract the armature of this relay. The right hand winding, however, of this relay is ediciently so arranged that the vcurrent in one direction ywill oppose. the erect of the lett/hand winding, but with current in the othery direcf tion both windings will'co-operate to'attract the armature of the relay.

in rup'ting or timing device with parts referred to as interrupter :#:1 Yand interrupter#2. These two interrupters may be'inthe form of insulating cams mounted on 'aV constantly a two-wire syswound and is Figs. 1 and 2 there is shown an interrotating shalt, or maybe of any structure in which the contacts 2O and 21 or Fig. 1 are closed for intervals in the sequence and relation indicated by Fig. 1. VOne of these sets of interrupters or interrupting device will serve for all the circuits located at one oiiice.

It is believed that the invention will best i be understood bydescribing the method of establishing a telephone connection from a substation indicated at A to a called substation indicated at B. lVhen the subscriber at Afinitiates a call by removing his receiver from itsswitchhool, the line relay 5 of the line switch, individual to thecalling line, is energized to start the Voperation of the line switch to connect this line to an idle trunk.

' `rlhe energizing circuit *for* the slow releasing relay 5 extends from grounded battery, winding of this relay, upper back contact and armature of relay 6, through the upper side of the calling line and its substation circuits, through the lower side of the line,

' operating circuit is closed for the motor ci l magnet 8 of the -lineswitch, this circuit extending 'from grounded battery, winding, back contact and armature of the motor magnet 8, outer armature and contact of line relay 5, lower contact and armature or the cut-off relay 6, test brush 9, oi the line switch, test Contact 11 to ground over the test conductor o-busy trunks.

Let it be assumed that the trunk with which the brushes of the line switch were in operative relationwas busy, under which condition a guarding potential exist-s on the test contact corresponding to V11 of this trunk, being applied from ground, through the left hand armature and front contactV of relay 10 and conductor 12. Under the control of the motor magnet and its operating circuits, vthe line switch advances its test brushes until the test brush 9 engages the test contact 11 of a trunk that is disengaged, a condition which is indicated by the absence of potential on its test contact. As soon as the idle trunk is reached, the cut-oil?, relay 6 is operated ina circuit from grounded battery, winding, back contact and armature of the motor magnet 8, cut-oill relay 6, inner contact and armature of line relay 5 to ground. The Vcut-od relay through its upper armatures and front contactsextends the calling line to the line switch brushes 13and 14, and through these brushes closes a circuit forthe impulse relay 15 of the repeater. The impulse relay 15 is operated in this circuit, and at its armature and iront contact closes a circuit through the left hand winding of the primary release relay 16. The primary release relay attracts its armature, and closes a locking circuit for itselfV while lcontacts VE20 of interrupter .Tl/:1 are closed, and at its upper contact closes a circuit romground, through the lett hand Vwinding of the secondary release relay 10 togrounded battery. This last named relay attracts its armatures, closing a locking circuit 'ror itself while contacts l1 are closed, and at itsV lett hand armature and front contact extends a holding ground 'over conductor 1Q, test contactl 11, test brush 9, lower this operation interrupts the operating cir-V cuit oi` the line relay 5, but this last named relay is designedv to release its armature slowly so that it maintains the original yenergizing circuit of the cut-oil relay 6 until the holding circuit has been completed at the relay 10 of the repeater. The repeater is now in condition to receive impulses from the substation sender S over the impulse circuit including the impulse relay 15; This impulse is ordinarily closed for'an appreciable interval beforethe subscriber starts sending impulses. The subscriber now operates his sender S to transmit a series of impulses corresponding to the'lirst digit of the wanted number. series of impulses, the'impulse relay 15 vibrates its armatures. At the irstretraction of the inner armature of the impulse relay 15, a circuit is closed from ground, outer right hand armature of the secondary release relay 10, left hand winding of the primary change-over relay 18 to grounded battery. The change-over relay attracts itsV armature and at its upper contact closes a circuit from ground, through the lower winding of the secondary change-over relay 19 to grounded battery. VThis last named relay attracts its armatures and at its lower armature and front contact closes an impulse circuit for the first selector switch at the distant otlice, as will be described. At the lower contact and armature of the primary change-over relay 18, a locking circuit is closed through the right hand windingV of this relay, contacts 20ct the interrupter .#1, to grounded battery, provided these' In response to this contacts 'are closed. The purpose of this locking circuit will be hereinafterdescribed.

It should be noted that the relation between the sets ofcontacts of interrupter #1 and interrupter .#2, should be such that the release magnets will not be operated in Vre spense to the directive impulses which are of short relation, butwill permit the opera.

nr CM) tion of thesemagnetsin response to a long interruption ofthe impulse circuitln response to the remaining impulses of this circuit, the impulse relay l Will retract its armatures, but at this time an impulse reperiti-'ng` circuit is closed for the impulse Vrelay 22 ot the selector from grounded battery, right` hand Windinpoil this relay, uppermost armature and bacl'r contact of the switching,` relay 23,*loyver irontV contact and armature ot' the secondary change-over relay-19, outer right hand armature and front contact of the impulse relay l5 of the repeater, inner armature and back contact oiP4 switching' re lay 23, left hand Winding` of the impulse relay 22 to ground.

In response to this firstseries of' impulses, the impulse relay 22 viblates its armature. [it the first Closure oli' the impulse circuit when the impulse relay 22 attracts its armature, a circuit for the primary release relay 243,-' is closed from grounded battery, lett hand Winding otthis relay. through contact, andA armature of' the impulse relay 22 to ground. ln the event that the contacts of the interrupter itl at the distant otlice inY which the selector is located are closed, a circuit is completed from grounded battery, through contacts 25, conductor 26, and right hand winding of" the primaryvrelease relay 24: to ,eroundl Under the control' of 'this circuit the primary release relay is intermittently locked' operatedfor a purpose to be pointed out;

As soon as the upper Contact and armature otx relay 24 is closed, a circuit is completed through the lett hand Winding` of the secondiary` release4 rela-y 27, and in the event that the contacts 28 of the interrupter #2 are closed, a circuit is completed' from grounded battery, through contacts 2S, conductor 29, right hand Winding` ofthe secondary relay 27, its contact and armature to ground.

lt should be noted at this point that the circuit for the release magnet oi the selector is controlled at the back contact ofthe secondary release relay 27, back contact ol' the sivitching'relay23, and back Contact ot the impulse relay'22. During` the reception oiJ properly timed'v impulses from the repeater; the circuit ofthe release magnet 30 is closed at the back` contact of the impulse relay 22; but at this time the secondary release relay 27-will be operated so that the release magnet circuit is not completed. It

will be seein that before the release of the selector switch can be effected"n the secondary release relay 27 must be deenergized, but this relayis held operated' first in a circuit completed at the armature and contact or" the primary" release relay 24, and also over the locking' conductor 29. In order to effect a release, it isl necessary ior the impulse relay L 22 to retract itsarmature Which opens the original operating` circuitl of the-primary release relay 24'. 'Then in the event that the contacts 25 of interrupter #l are closed, the primary release relay: 24 Will be locked operated until the interrupter r/.tl has rotated to open the contacts 25. Although the original operatingV circuit of the secondary release relay 27 is open at the contact and armature f of relay 24.-, itV Will be heldilocked until the contacts 28 oli interrupter :#2 have passed through a complete closed cycle. T he period during which vthe contacts 28 of interruptor #2 are closedis of such length that the impulse relay 22l will have attracted its arma-- tures it the interruption of the impulse circuit is due to sending impulses and not due to a loner release impulse.

Having thus described how the release of the selector is prevented in response to properly timed impulses in response to a subscribers substation sender, it Will noW be described hou7 the selector is operated in response to these directive impulses repeated by the repeater from the substation sender. ln response to each impulse, rtheimpulse relay 22 of the selector retracts its armature, and since the Vsecondary release relay 27 is energized during' the transmission of properly timed impulses,Y a'circuit is closed for the primary magnet 3l of the selector eX- tending from grounded battery,-Winding of this magnet. left hand Winding ot the primary change-over rela-y 32, 'outer front contact and armature of relay 27, lower back contact and'v armature ot relajY 23, and baclr contact and armature of the impulse relayV 22 to `around. In response tofeach of these directive impulses relayed from the repeater, the prim-ary motor magnet- Slof the selector switch advances kits brushes step-by-step to select a group of trunks through which the Wanted subscriber can be reached. The primary change-over relay 32 is operated in series with the primary motor magnet 3l and attracts its armatures. At its armature and Contact a locking circuit is closed for itself through its right hand Winding, conductor 26, contacts 25 of the interruper #l to groundedbattery in the event that the interrupte'r is at that time in closed position.`

lilith the primary change-over `relay 32 operated, a circuit is closed *for the secondary change-over relay 34 extending yfrom grounded batter-y, left hand Winding of this relay, and front contactand armature of rei lay l32`to. ground; VThe secondary changeover relay 3ft when op y from ground throughits lowercontact and armature andrigrht hand AWinding, conductor 29A and contact 28 `to grounded battery in the eyent that the interrupter i/:2s in such position that thecontacts 28 are closed; It will be notedv at this point that the interrupters and like-Wise control the change-over from the primary tothe secondary operation ated closes aV circuit of? the selector switch by measuringan interyai of time greater than the interval between the'impulses of a lseries and less than theinterval between two series of impulses. In'othe1 words, the secondary change-oyer relay has its circuit closed either at the primary change-over relay 32 or through its locking circuit at thecontacts 28 of inter-` rupter #2, Vas long as Vimpulses are being received by the selector switch but as soon as atime interval greater than that between impulses of series has passed, the locking circuit controlled at contacts 28 will be opened and' change-over relay 34 will retract its armature. After the contacts ofthe cti' normal switch haye been closed after the first primaryY step of the selector and as Vsoon as the secondary change-over re-lay 'is'operatech the marginal relay 36 is operated in a circuit closed from grounded' 'battery its winding. contacts 35 and upper contact'and armature of relay 34 to ground. Relay 36 as soon as operated is locked energized in a circuit traceable from grounded battery, winding of'this relay, contacts 35,

conductor 3T, armature and back contact of the secondary .motor magnet 38, right hand front contact and armature of relay 36, conductor 39 land inner right hand armature and front Contact of relay 27 to ground.

Assoon as the secondary change-over relay deeucrgizes and with relay 36 operated.l

a circuit is closed for the secondary motor magnet 38, from grounded battery, its wlndving. left hand contact and armature of relay 36, and back contact and armature of secondary change-over relay 34 to ground. Under the control of' this circuit the secondary motor magnet advances the brushes ot the selector into .engagement wit the first trunk of the Aselected group. In the event that this trunk is engaged, a guarding potential isi-:applied vto itstest contact from hand armature of the relay 4l of its associated When the test brush 42 engagesa busy test terminal 40 Vof an engaged trunk. theV relay 36is operated'in a circuit extending from groundedv battery, its winding, off normal contacts 35` conductor 37, armature and back contacts of secondary motor magnet 38; conductor 43, inner lower back contact and armature o'relay 23, conductorfl44. test brushr42 and test terminal 40 to ground, i lVith the relay 36 again ener'- gized, the operating circuit of the secondary motorrmagnet38 is again closedV and this magnet will advance the selector brushes one step. lt will thus be seen that duringthe time that theselectoris testing busy trunks,

the relay 36 'is operated to close a circuit for the secondary motor magnet, and the operation of this motor magnet'opens the energizing circuit of the relay V36. This operation continues until the test brush 42 engages an l ungrounded test Contact at which time a circuit isv closed from grounded battery, winding of relay 3G, ofi normal contacts 35, conductor 3T, armature and back contact oi' secondary motor magnet 38, conductor 43,

vwinding of switching rela-y 23 and vleft hand contact and armature ci relay 27 to ground. The switching relay 23 is operated in this circuit to extend the selected trunk to the brushes 45 and 46 of its selector switch.

The relay 36, however, is marginal and will winding of relay 50, winding of thev impedance coil 51, lower back contact and armature of relay 19, and outer right hand armatureV and front contact of relay l5, inneruppor armature Vvand front contact of relay 23, selector brush 46, over the lower side of the selected,` trunk, leithand con-V tinuity spring and baclrcontact of relay 49 and left hand winding of the impulserelay 48 to ground. ated in this circuit and attracts its armature to close a circuit 'from ground, its armature and front contact, lett hand wind- `ing of the primary release relay 52 of the connector to grounded battery.'V Relay 52 is operated in this circuit and as soon as contacts 25 are closed during the rotation of interrupter q'zfzl, relay 52 is locked operated through contacts 25, its right hand winding, and front contact and armature to ground. VAlso at the upper contact and armature of lrelay 52, a circuit is closed through the left hand winding circuit for itsel'from ground, its armature,

front contact and right hand winding toYV grounded battery soon ascontacts 28 are closed in the operationo interrupter The impulse relay is actu-V f of 'secondary release relay 41 to grounded battery,V and this last namecL relay closes a locking .2. Also at upper Vcont-act and armature Y of relay 4l, a circuit is closed'from ground, through primaryoi normal contacts 53, which' contacts are opened after the'iirst vertical step of the connector, left hand winding of the change-over relay'v 54 to grounded' battery.

a. locking circuit for itself through its right hand winding whenever the contacts V28 or" interrupter #2 are closed; At the middle armature and iront contact of this relay a second locking circuit is closedV for the The Yrelay 54 is thus` [caused to attract its armature, and at its f innermost armature and iront contact closes recaen relay 54:, through its left hand winding as long `as the primary changeover relay 55 has its upper contact and armature closed. At the bach contact and middle armature otrelay :5v-fi, the original energizing circuit of the tertiary change-over relay is held open during the primary operation ot the connector switch. it the outermost armature and front contact of relay 5da break poi-nt in the operating circuit of the primary magnet 56 ofthe connector is closed, and at this back Contact and armature, an epera-tingcircuit of the secondary motor magnet 5T of the yconnector is held open.

ln response to the tens series of impulses repeated by the repeater, impulse relay #18 vibrates itsy armature and at its iron-t contact intermittently closes a circuit through the left hand winding of the primary release relay 52, and at its back Contact closes a stepping circuit for the primary motor magnet 56 et the connector `from ground. armature and back contact ot the impulse relay, outer armature and front'contact oit the secondary release relay el, lett hand winding of primary change-over relay 55, @Literariost armature and front contact of the secondary change-.over relay 54, winding of the primary motor magnet 5.6 to grounded battery. ln response to each poi' these closures oit they operating circuit of the motor magnet, this magnet advances the brushes 58, 59 and GO of the connector in a primary `orgroup hunting movement until they are directively placed in operative relation to the group of lines in which the wanted line terminates.

lt should be noted that the circuit of the release magnet 5l of the connector extends from grounded battery through the winding ott this magnet, primary oil normal conv tact 62. outer bach contact and armature of secondary release relay l-l, back Contact and armature of impulse relay 48 to ground. During the transmission of impulses to the inipulse relay, this relay closes its back contact, but the release circuit is held open at the back contact and armature of relay ll-l, and it will be seen that the secondary release -relay il is held operated during the interval that properly timed impulses station sender are being relayed to the iinpulse relay, but as soon as a release impulse is conveyed to the connector switch, the impulse rela-y willbe cle-energized t r a longer `interval than that caused by the receipt orp a directive impulse, and the secondary release relay lll de-energizes. ls was pointed out in connectiongwith the selector circuit,

the rotating interrupters #l and :5:2 are` so arranged that ati-ter the primary release relay isionce operated, it is locked in this vcondition through the' contacts 25 for a certain interval the length oit time depending upon vthe position of interruatei' from the sub,

connector will not be .released during the impulse ycircuit interruptions employed Vin setting the connector switch.

fitter the transmission of the tens series of impulses a slight. period of time intervenes before the last series of impulses are sent troni the substation impulse sender. During .this period the impulse relay 48 holds its armature attracted and thereby. interrupts the original `energizing circuit of` the Vprimary change over relay 55, vand as soon as interruptor #l has rotated to open its contacts 25, the locking kcircuit is broken` for the relay 55 causing it to Cle-energize. The cle-energization of relay 55 .opens the locking circuit including the left hand winding ,ol1 relay 54.- and its middle armature and liront contact, and `when contacts 2S of the interruptor #2 are open the loching circuit including the right hand winding ol" relay 5a' is broken, and this relay retracts its armatures. The calling subscriber thereupon operates his substation sender to transmit impulses `corresponding to thelast digit et the Wanted number ot the subscribers line, and this last series of impulses is repeated by the. repeater to the impulse relay i8 `of the connector switch. ln response to this last named series'of im= pulses the relay a8 vibrates itsarmature, at its `front contact preventing the release of the connector switch, and at its back contact closing a circuit trom ground through the outer armature and :trent-contact of re lay lil, lelt hand winding of .the primary change-over relay 55, outer-most armature and baclr Vcontact of secondary changeover relay 54, outer armature and back contact et test relay G3, conductor 64, lower-most armature and bach contact of the .cutthrough relay 65, winding of the secondary motor magnet 57 to grounded battery. ln response to the lirst retraction of the armature of the impulse relay e8, the secondary motor magnet 57 and the primary ,changel over relay are energized in series; the secondary motor magnet lto advance the connector brushes one step, and the changeover relay 55 to close a circuit from ground3 its armature and upper contact, armature and bach 4Contact ot relay 54, right hand winding oi' the tertiary change-over relay 95 to grounded battery. This last named relay when actuated closes a locking circuit for itself trom ground through its armature, front contact and left hand Winding to grounded battery Whenever -contacts 28 are closed. Also as soon as relay 95 is actuated, a substitute circuit for the secondary motor magnet 57 is closed 'from ground edV battery, its Winding, lowermostrcontact and armature of relay 65, front contact and right hand armature of relay 95, outermost back contact and armature of relay 54, lett hand Windingl ot' relay 55, outermost iront contact and armature of relay 4l, and back contact and armature o*l irnpulse relay i8 to ground. The purpose ot the first described operating circuit for the motor magnet over conductor 6a is -to operate the motor magnet betere the relay 95 [is actuated, which does not taire place until the first secondary impulse. Thereatterit is desired to control the secondary motor magnet '57 f independently of the test relay 63, since at the time when the test brush 60 isengaging the test contacts of busy lines,

Vthe test relay .63 is .monientarilyoperated Y relay retracts its armature and opens. the

" is idle.

energizing circuit including the right hand Winding 0f the tertiary change-over relay 95. After this has taken place, the locking vcircuit. including the left handV Winding of relay 95 is opened at the contacts'28 of the interrupter #2. During the period before the tertiary change-overl relay de-energizes and While the test brush 60 is engaging test terminal 68 of the Wanted line, the test of this line is eifected. Y.

Let it be assumedV that the Wanted line Under this condition a circuit is closed from grounded battery,vthrough the resistance 69, Which may be the cut-ofi' relay ofi the Wanted line, test terminal 68,. test brush 60, outer armature and back contact of relay 95, upper Winding of the .cutthroughrelay 65, inner armature and back contactV of test relay 63, lett hand iront contact and armature oi relay lll. to ground. Relay is operated inthis circuit .and at its lowermost Varmature and bach Contact opens thecontrolling` circuit of the secondary motor magnet 57. At its contact 70 and armature, it applies a guarding potential on thetest terminal of the wanted line to pre` Vent its seizure by Isome other connector switch, While at its contact 7landl armature it Vopens the test circuit of relay G3, and at its innermost armature and iront contact closes a locking circuit Vfor itself over con" ductor 72 to ground at the upper Contact and armature of relay el. -At the upper armatures and contacts of relay (i5, a signaling circuit isV closed from the interrupted source ol' signaling current indicated at Gen. inner baclf. contact `and armature of the slonl operating trip relay 73, innermost upper armature and' contact relay 65, brush 59, line terminal 67, through the line circuits and bell at the Wantedstation l5, line tern'iinal GS, connector brush 58, uppermost contact and armature ot relay uppermost armature and back contact ot the trip relay 73, upper VWinding of this relay to grounded battery. The source of ringing current is thus intermittently applied to the called line to actuate the call signal or bell at the station B. 'The trip relay 7 3 is so designed that it Will not operate until the called party at substation B responds byreinoying his rccciyer from its switchhool, whereupon it is operated to disconnect lthe source oi' sigf vnaling current and to extend the talking circuit through itsgupper armatures and 'front contacts. A locking circuit closed through the lower Winding, 'front contact Vand armatureV or trip relay 73, overV conductor 72 holds this relay operated to maintain theV continuity oi the talking circuit and to prevent the reapplication ot signaling current to the called line. e

As soon as the trip relay ias closed its upper armatures and ront contacts, a cir cuit Vis closed tor the called line talkingbattery, Yfrom battery right hand Winding of relay i9 over the upper sideoi the trunk and called line in series, lowerrside ot' the trunk, lett hand Winding ot relay 49, lower 'front contact and armature of relay 75, con ductor 72, contact and armature of relay v-ll to ground.- Relay 9 is operated in this circuit .and at its continuity springs and contacts ferses the direction of thebattery in the circuit through the left Winding ci' the' impulse relay 48, through the selector brush 45, upper-most front contact and armature oi relay 23, right hand `Winding ot relayy 50, Winding of impedence coil, lower bacli contact and armature or relay 19,; right hand armature and iront contact of inipulse relay l5 ofthe repeater, inner upper armature and front contact or relay Q3, brush and right' hand Winding of relay 48.

The current in the circuit just described is in such direction that the right hand Winding of the electro-polarized relay 50 adds its energizing eiiiectY to that of the ineiiicient lett hand Winding of relay 50, whereupon the relay 50 attracts its armature-and closes a circuit for operating the relay 75. This last named relay through its continuity springs Cil 1,463,597@ Y y a and contacts reverses the directon of the talking battery led to the calling party through the windings ot relay l5.

lietit be assumed that the wanted station B was engaged at the time when the connector brushes 58, 59 and GO were pla ccd on its line terminals G6, G7 and 68. It will be recalled that the tertiery change-over relay 95 is held operated 'for a short interval after these brushes have been placed on the wanted line terminals, so that it the wanted line is busy a circuit is closed from grounded "battery, winding of the test relay 63, contact 7l and armature et relay 65, continuity spring and armature ot relay 95, test brush GO, test terminal 68 and through a multiple terminal and test brush corresponding to 6() ot the connector which has previously seized the want-ed line, to ground over an armature and contact oif -that connector similar to the armature ot relay (55 and contact 70. As soon as the test relay 63 is operated, it closes a. locking circuit tor itself' from grounded battery, its winding, contact 7l and armature of relay 65, continuity spring olf relay 95 which is cle-energized, contacts 76, conductor 77, inner trent contact and armature olE test relay 63, lelt hand t'ront contact and armature oit relay il to ground. rlhe test relay. will therefore be loclred operated until lthe call is abandoned,l and this prevents the cut-through relay G from eX- tending the talking circuit to the brushes 5S and 59 which are in engagementwitli the terminals et the wanted line. Also as long as test relay G3 is operated a busy tone is transmitted to the called line from the source oi" busy current indicated at Busy, lcit hand armature and front contact of rely 63, over the circuit which has been eX- tended from the calling line. o

llllhen the calling party abandons the call because the called line is busy or terminates the call at the close ot conversation, the release of the connection is effected in the following manner: llhe calling subscriber replaces his receiver on `its switchhoolt, thereby interrupting'the circuit of the impulse relay. 15, through which battery has been ted to the calling line. The impulse relay retracts its armatures and at its front con "f lower armature and Jfront contact ot switchtact and inner armature opens the original energizing,winding ci the primary release relay 16. lt the release takes place at the time whencontactsi of interruptor :trl are closed, primary release relay 16 will he held operated over the circuit previously described until these contacts are open. is

soon as the relay 1G retraets its armatures it opens the original energizing circuit of the secondary release relay l0 of the repeater, and thereafter thecontacts 2l of in terrupter #2 'are opened following their closure. After a complete closed period after relay 16 retracts its armature, the

fit the lett hand armature audit-ront contactIY or' relay l() the holding conductor l2 which has maintained the cut-off relay G operated,

is opened and this relay cle-energizes to eitect the release of the line switch.

At the outer right hand armature and front contact ot-the impulse relay l5' of the` repeater the impulse circuit of the impulseV y relay 48 of the connector is opened permit-v ting this relay to retract its armatures. rlhe primary release relay 52 and the secondary release relay ll co-operating with he interrupters :#21 and 2 measuie oli" an interval of time greater than that necessary for the transmission ot a directive impulse to the connector switch. After this interval oi" time has elapsed, the secondaryvrelease relay 41 will retract its armatures and will close a circuit for the release magnet 6l' ci? the connector switch from grounded loat-Y tery, winding of this magnet, primary oli" normal Contact 62, outer bach contact and armature of relay al, and back contact and armature of the impulse relay to ground. Under the controlof this'circuit the release magnet 61 is operated until the connector isv and the lower winding ot this relay is` also simultaneously opened. ln the event that the connector switch has tested a busy line and the test relay 63 therefore locked'v operated, this previously described loclr'ingvcircuit is interrupted at the left yhand trent contact and armature ot the secondary release relay al. This same contact andarmeture of relay 41 also removes theground from the test contact 40 of the trunk leading to the connector used, and opens the holding circuit previously described'as eX- tending through conductorl 44, innermost lease magnetBO of theselector switch, whichV circuit extends from grounded battery,

winding ot this magnet` off normal contacts 80, back contact and outermost armature ot' secondary release relay 27, lowermost'contact and armature of relay 23, and back contact and armature of thevimpulse relay sponsive to impulses transmitted over the two sides thereof, a set of contacts for said impulse relay, a second relay operating in substantially the same time interval as said impulse relay, means responsive to saidv impulse relay for directively operating said automatic switch in selecting a desired outgoing line, a set olf contacts for said second relay, a release magnet for said switch and ay circuit therefor extending through conL tacts of said relays, and mechanicalrderice for controlling the operating circuit of said second relay. f l

2.111 a telephone system, an incoming line, a plurality of outgoing lines, a switch for interconnecting said incoming1 line Vwith any ofsaid outgoing lines, an impulse relay connectahle tosaid incoming lline and responsive to impulses transmitted over the two sides thereof, a set of contacts tor said impulse relay, a second relay operating iii substantially the same time interval as said impulse relay, said second relay having sets of contacts, means responsive tc said impulse relay for directively operating said automatic switch in selecting` a desired outgoing line, a. release magnet for said switch anda circuitL therefor extending through contacts of said relays, and 'a rotating dovice for controlling the operating circuit of Y said second relay.

3. In a telephone system, anA incoming' line, a plurality of outgoing lines, .a switch for interconnecting said incoming line with any orP said outgoing lines, an impulse relay coniiectahle to VsaidV incoming line and. re-l sponsive to impulses transmitted over the" twosides thereof, al second relay operating inesuhstantiallj-fr the same time interval las said impulse relay, means responsive to said completed,

impulse relay for directively operatine` said automatic switch in selecting a desired eut-k *going line, a release magnet for saidiswitcli and a circuit therefor having two break Y points controlled at the contacts ot said relays, and a unidirectional rotarytiming device for controlling'the operating circuit of said second relay.

4. In a telephone system, an incoming line, a plurality ot outgoing lines, a .switch for interconnecting said incoming line with any of said outgoing lines, an impulse relay responsive to impulses transmitted tronia distant point over the two sides of the incoming line in series, a second relay operating in substantially the same time 'interval as said impulse relay, sets 'of contacts for said impulse relay and ji'for said second relay, amotor magnet 'tor operating said automatic switch, a circuit theretor extending through normally closed contacts at said impulse relay and normally open contacts at said second relay, said normally closed contacts heing intermittently closed in response to impulses, and said normally opened contacts being closed during a series of impulses, a mechanical timing device, and a circuit for said second relay closed at said device.

5. In. a telephone svstem, an incoming line, a plurality of outgoing lines, a switch for interconnecting said incoming line with any of said outgoing lines, an impulse relay responsive to impulses transmitted over said incomingline, operating means for said switch controlled at said impulse relay, a release mechanism and oill normal contacts for said switclna release relay controlling said release mechanism, a release circuit for said release-'mechanism extending through contacts cit said release relay and saidv im pulse rela 7 and said oil-normal contacts, a Y

primary and secondary operatingmeans for said switch responsive to the operation of said impulse relay, a release relay, sequence controlling mechanism for determining the operation ot said primary and said secondary operating means, third relay controllingsaid mechanisin, and a circuit for said relay closed at front contacts oi" said release relay and hack contacts of said impulse relay, a release magnet and olf normal contacts for said switch, a circuit for said magnet extending through said off normal contacts and hack contacts of said release and impulse; relays, and a timing device 'through which circuits for said third relay 'and said release relay are 7. In a telephone system, an incoming` line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said .outgoing lines,

primary and secondary operating magnets for advancing said switch, an impulse controlling device responsive to impulses transmittedover said incomingline for directively operating the primary and secondary `operating magnets, 'a test relay for testing the busy or idle condition of a selected line,

a plurality of relays for sequentially conlOl) trollingtlie circuits of said primary and said secondary magnets and said test relay, and a rotary timing` device associated with said automatic switch co-operating with said impulse rely to control said plurality of relays.

8. In a telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any otsaid outgoing lines, primary and secondary operating magnets for advancing said switch, an impulse relay responsive to impulses transmitted over said incoming line for directively operating the primary and secondary operating magnets, a test relay tor testing the busy or idle condition of aV selected line, a plurality of relays for sequentially controlling the circuits of said primary and said secondary magnets andsaid test relay, and ra vrotary timing device associated with said automatic switch co-operating with said impulse relay to control said plurality of relays.

V9. ln a telephone system, an incoming line, a plurality ot outgoing lines, an automatic switch for interconnecting said in coming line with any of said outgoing lines,

an impulse relay responsive to impulses o'r' said release mechanism, a circuit fior said primary magnet including said sequence relay and completed at the front contacts ot said release relay and back contacts ot said impulse relay, and a rotary mechanical device associated with said automatic switch for controlling the operation of said im pulse relay. l

l0. In a telephone system, an incoming line, a plurality ot outgoing trunks, an automatic switch for interconnecting said incoming lin'e with any of said outgoing trunks, an impulse relay responsive to impulses transmitted over said incoming line, primary and secondary operating means for said automatic switch, said primary operat` ing means being responsive to said impulse relay, said secondary operating means being` controlled over busy outgoing trunks to advance said switch to seize an idle oute going trunk, a sequence controlling relay, a sequence controlling mechanism governed thereby for preventing the operation ot the secondary operating means, a circuit for the primary operating means serially including a winding of said sequence controlling relay and controlled at said impulse relay, a rotary timing device associated with said automatic switch and a circuit including a second winding of said sequence controlling relay completed at said device.

l1 1.. ln a telephone system,an incoming line, contacts in said incoming line, a plurality of outgoing lines, an automaticswitch for interconnecting said incoming linepwith any of said outgoing lines, an impulse relay controlled over said incoming line, means for operating said automatic switch controlled by said impulse relay, a second relay for operating the contacts in said incoming line, a release mechanism and otf` `a sequence controlling device including a group of relays for determining theprimary and secondary operation of said switch, a release magnet` for said switch, and means `including a group of relays for controllingy the operation ot' said release kmagnet, and a unidirectional rotary timing device at said automatic switch and circuits for said groups of relays completed at said timing device. l f

13. ln a step-by-step mechanism, in c0nibination with a movable element, means for operating said movable element, a motor magnet for actuating said means a-nd a locke ing device, oi a release magnet for disengaging said locking device, a circuit for the motor magnet having normally opened contacts and a circuit for the release magnet having normally closed contacts, a relay for closing the motor magnet circuit and opening that ot the release magnet, a normally open circuit for said relay, a rotary timing divice, a lockingcircuit for said relay closed at said rotary vtiming device, and a source of current supply for said circuits.

i4. ln a step-by-step mechanism, the com` bination with a movable element, means 'for operating said movable element, a motor magnet ior actuating said means, and a locking device, of a magnet for releasingsaid locking device, circuits for the motor and release magnets, the former having normally open contacts, and the latter normally closed contacts, a mechanicaltiming device associated with said movable element, a relay for reversing the position oi? said contacts, a normally open circuit for.v

the relay, means for closing and opening ksaid circuit, and a locking circuit for said relay closed on the actuation thereof at said mechanical timing device, a source oia current supply tor said circuits, and means lOO Viio

'.switch, a release magnet, a release relay, an

impulse relay, an energizing circuit for said release magnet and a switch shaft, said energizing circuit adapted to be closed wheneverthe switch shalt is off normal and the impulse and release relays are deenergized, a mechanical timing device and a plurality of circuits for said release relay, one of which is closed at said mechanical timing device, and means for maintaining one or another of said circuits of the release relay completed during the operation of the impulse relay.

1G'. A telephone system comprising an automatic switch, an impulse relay, means for energizing said relay upon connection made with said switch, a release relay, a mechanical timing device and circuits for the release relay controlled by said impulse relay and by said mechanical timing device, contact controlling means governed by said release relay duringl the connection and ad justment of said automatic switch, and a release circuit for said switch controlled by said impulse relay and by said contact controlling means.

17. A telephone exchange system, comprising Ya two conductor circuit, associated automatic switch mechanism having waiting contacts divided into groups, and a cooperating movable contact, means outside of said switch for rendering some of said waiting contacts busy, means for advancing said moving contact to a desired group of waiting contacts in response to variations of current transmitted over said circuit, means for starting said moving contact in search vof an idle contact in that group in response to another current variation transmitted over said circuit, means for continuing the movement or' said moving contact in said searclnand stopping it only when an idle contact is reached, releasing mechanism for said moving contact, and a unidirectional rotary timing device controlling said release mechanism.

1&8. In a telephone system, a subscribers line, substation apparatus on said line including a receiver, a transmitter, and switchhook contacts normally closed by said receiver, an impulse sender included in saidV line, a plurality of trunks, each terminating in a selector switch, means for automatically connecting said subscribers line with an idle trunk and its selector switch, trunks terminating in groups at said selector switches, means controlled by said impulse sender for directively operatingsaid selector switch to select a desired group of outgoing trunks, means for thereafter causing said selector `switch to automatically hunt for and seize an idle trunk in the selected group, release mechanism for said selector switch, a ,com nector switch individual to the selected trunk, means for directivcly operating said connector in group and line selecting movements to select an idle Awanted line, animpulse relay, an impulse circuit serially extending through both sides of the Vselected trunks and subscribers line' and arranged to transmitV impulses from said impulse sender to said impulse relay, release mechanism for said connector switch, and a mechanical timing device common to said selector and Vconnector for controlling said release mechanisms. Y

19. In a telephone system, a calling line and a called line to be switched into con nection, a non-numerical switch and a plu rality oi' independently adjustable numerical switches for inclusion in the connection, each of said numerical switcheshaving an indi`v vidualv adgustmg magnet, a common relay for transmitting currents to said magnets insuccession, restoring mechanism for said nonf numerical switch, means associated with said relay andY controlled thereby to govern the operation of said restoring mechanisnnand means including a mechanical timing device for ydisabling said restoring means during the actuation of said relay.

20. In a telephone system, a calling line and A a called line, means including non-numerical and numerical switches for inter-connecting said lines, a repeater interposed betweenV een tain of said switches, said repeater including an impulse relay, an impulse circuit over which said numerical switches are controlled, by said impulse relay, means including a relay ifor preparing said impulse circuit, restoring mechanism for said switches, means including a release relay in said repeater for controlling the restoration of switches at one side of the repeater, and amechanical timing device for controlling said release relay and the relay for preparing the impulse circuit.

2l. In a telephone system,ran incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said outgoing lines, an impulse sender associated with "said incoming line, means responsive to the operation of said impulse sender 'for advancing said switch through group and line selecting movements, controlling means for causing theoperations of said automatic switch to occur in Vproper sequence, releasing means for said switch, and a mechanical interrupting vdevice operating throughout the period of time that said switch is in use for causing the operation of said controlling means at the proper time and for preventing the operation of the releasing mechanism during the directive operation of said automatic switch.

22. In a step-by-step mechanism, the combination with a movable element, operating lli) for eliecting the secondary movement of said movable element, ot circuits for said magnets closed in succession, each of said f circuits having normally closed and normally open sets of contacts, a relay for controlling the set off closed contracts, an operating circuit leading to the controlling relay and means for sending impulses of current thereover, an electromagnetic device controlling the set of' normally open contacts, a timing device common to a plurality of said movable elements andV a circuit for said electromagnetic device, means governed by said controlling relay and said timing device for operating said electromagnetic device, and a source of "current supply for said circuits.

23. In a step-bystep mechanism, the combination with a movable element, primary and secondary motor magnets for advancing said element successively through its primray and secondary movements, a circuit controlling device provided with an operating magnet for determining the sequence of operation ot said primary and secondary motor magnets, other movable elements, a timing device common to a plurality of said elements, a relay co`-operating in the control oi' said operating magnet, circuits for said primaryand secondary motor magnets, each of which serially includes said relay and means co-operating with said timing device and relay -for controlling the operation of said primary and secondary motor magnets and the magnet of said circuit controlling device. Y

24. In combination with a normally open operating circuit, an impulse .transmitter arranged therein, a progressively movable switching mechanism comprising a normally 'inoperative motor magnet and an electromagnetic device which is adapted to control the operation of the motor magnet in synchronism with current impulses from said transmitter, means actuated upon the closing of the operating circuit for rendering the motor magnet operative, said means being adapted to retain said magnet in operative condition only during the transmission of successive current impulses of given frequency over said circuit, other similar switching mechanisms and a mechanical timing device common to a plurality of said switching mechanisms and cooperating in the control ofsaid last mentioned means.

v25. In a telephone system, an incoming line, a plurality of outgoing lines, a switch for interconnecting said incoming line with any of said outgoing lines, an impulse relay operated over said incoming line and functioning to control the operation of said automatic switch, a sequence controlling device for controlling the sequence of operations of said automatic switch, releasing mechanism tor releasing said switch, a plurality of relays for controlling said device and said releasing mechanism, said relays being provided with two windings, one windingroi each of said relays being responsive to the Aoperation of said impulse relay and the other winding of eachof these relays being controlled through seli locking circuits, each self-locking circuit being controlled by one of said last mentioned relays.

26. In a telephone exchange system, comprising a control circuit, associated automatic switch mechanisms each having waiting contacts divided into groups and a cooperating moving contact, a primary magnet and associated means for stepping said moving contact to a desired group of waiting contacts, a secondary magnet and associated means for stepping said moving contact to a desired contact in that group, primary and'secondary electromagnets :tor 'controlling said magnets, means for energizing and deenergizing said electromagnets by closing and opening said control circuit to operate said primary and secondary mag nets to bring. about the desired movements ot said moving contact, and means including L a time measuring device common to a plurality of automatic switch mechanisms for determining the period of operation of one of said magnets. 1 I

27. In a telephone exchangesystem, a line circuit and automatic switches for connecting the same with called circuits, a relay responsive tov all changes in the line circuit and having front and baclt contacts, a time measuring device common to a plurality of automatic switches, a pair of relays connected to said contacts'respectively and being jointly controlled by said line relayl andr the time measuring device, and operating circuits for one of said yswitches jointly controlled by said relays.

Y 28, In a telephone exchange system, a plurality of metallic line circuits and means for interconnecting them, comprising a number of automatic selective switches and link circuits, a time measuring mechanism common to a plurality of linlr circuits, electromagnetic actuating and controlling means associated with each link circuit, certain of said electromagnetic means beingv in part con'w trolled by and Vbeing normally extended to said common time measuring mechanism, and means associated with a line when calling to produce groups of current changes therein, each group composed of changes oi different durations whereby the actuating and controlling electromagnets in the link circuits may be eectively energized.

29. In a telephone exchange system, a

group oflines, switches, a time measuring mechanismco'mmon to a plurality of said switches, conductors normally extending from said switches to said time measuring device, multiple terminals of said lines at said switches, multiple test contacts of said lines at said switches, a pair of talking conductors respectively terminating in brushes at Vsaid switches,V circuit controlling means at each switch controlled'in part by said time measuring mechanism, means 'for moving said switches over the terminals of the lines of said group, and an electromagnetic means at each switch for association with said test contacts and operating the circuit controlling means to maintain open the tall;- iiig conductors terminating in a switch -which is 4in engagement with the contacts of a line held by another switch.

30. In a stepeby-step mechanism, the combination with a movable element, aY motor magnet and means operated thereby for advancing said element progressively, of a cirj cuit for said magnet having normally closed and normally opened sets of contacts, a relay for controlling the set of closed contacts, an operating circuit leading to said controlling relay and means for sending impulses of current tliereover, electromagnetic means controlling the set of normally opened contacts, a circuit for said electromagnetic means, other movable elements, a time measuring device common to ,a pluralityof said movable elements andarranged to beoper` ated when any of said movable elements are in use, means governed by said time measuring device and said relay Jfor operating said electromagnetic means, and a source of current supply for said circuits.

` 3l. In a step-by-step mechanism, the combination with a movable element, 7a motor magnet and means operated thereby for advancing said element progressively, ot' a circuit for said magnet having normally closed and normally opened sets of contacts, a relay controlliiig the closed contacts and electromagnetic means controlling the open contacts, an operating circuit for said relay and means for sending impulses of current'tliere over to alternately open and close thecontacts controlled thereby, other movable elements, a time measuring mechanism com'- iiioii to a plurality of said movable elements, and a circuit for said electromagnetic means controlled in part by said time measuring mechanism, said last mentioned circuit functioning to maintain the contacts controlled by said electromagnetic means in closed poply current impulses to said'circuits, iii-com-` V bination with a metallic telephone .circuit and means for dispatching current impulses thereover to operate said devices, other switching mechanisms, and a continuouslyV operating time measuring Vmechanism common to a plurality orn switching mechanisms flor continuing the operation Vof said first device during the transmission a series of impulses over said metallic circuit.

33. In an automatic telephone system, a progressively movableV switching mechanism comprising a motor device which is normally inoperative and means at said'switch embodying two parts which operate conjointly by current impulses to render the motor device operative, the first of said parts being adapted to cause Va continued Vactuation thereoic in response to said impulses, other switchin@` mechanisms, a time measuring mechanism common to a plurality of said switching mechanisms and cooperating in the control of saidfiirst part, in combination with a telephone instrument circuit, and means for transmitting impulses. thereover to jointly control said operating parts.

84. In an automatic telephone system, a progressively movable switching mechanism comprising a normally inoperative motor device and means embodying two parts which operate conjointly by current impulses to render the motor device operative, the irst of said parts being adapted to beioperated to cause a continued actuation, 0ithe motor device, the other part beingadapted to operate independently to subsequently render the motor device inoperative upon the cessation of' its actuation, and a time measuring mechanism common to a 'plurality of switching mechanisms for determining the period 4of operation orx said other part,rin combina-Y tion with a telephone instrument metallic circuit, and means for transmitting current impulses ther-cover to control the coiijointly .operating parts.

In witness whereof, I hereunto subscribe my name this 23rd day of August A. D.,

VINFRED T. PGVELL.

iis 

